This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. G3BP (Ras-GTPase-activating protein SH3-domain-binding protein) was the protein that we identified as the main interacting partner of nsP3 in our Sindbis studies. To further characterize this protein, we isolated either the N-terminus or the full length protein and identified its interacting partners. One finding was that G3BP interacts with members of the nuclear pore complex and that these interactions seemed to be reduced following infection with Sindbis. Our studies of nsP3 localization using immunogold EM indicated the presence of a subset of nsP3 at the nuclear periphery. One resulting hypothesis was that nsP3 may also interact with G3BP at the nuclear periphery and induces the redistribution of G3BP to aggregates in the cytoplasm. This year to continued our work and performed immunoisolations of full length G3BP from uninfected cells and cells infected with Sindbis at two different stages of infection[unreadable]3 hpi, when minus-strand RNA is being produced, and 12 hpi, when mainly plus-strand RNA is being made.